The present invention relates to a communication apparatus and its communication method. The communication apparatus is able to detect an incoming-call signal during communication.
Conventional facsimile apparatuses having a memory for storing image data read from an original and transmitting stored image data in accordance with storing order or set transmission time are known.
Further, facsimile apparatuses which, if the destination apparatus is in communication status, stand by for a predetermined time to perform redialing, have been put into wide use.
Usually, a facsimile apparatus performs dialing to the destination apparatus as soon as possible after a transmission is instructed except in cases where a specific wait time is reserved. Accordingly, if the amount of transmission image data stored in the memory of the facsimile apparatus is large, or a multi-destination delivery (transmission of the same image data to a plurality of destinations) is designated to the facsimile apparatus, the facsimile apparatus sequentially transmits the stored transmission image data (hereinafter, transmission operation of this type is referred to as "sequential transmission").
In this case, the status of this apparatus is busy for a long period of time. If another facsimile apparatus, trying to transmit to the above apparatus in busy status, calls and repeats redialing, all the calls are rejected by the apparatus in busy status.
FIG. 6 shows a communication protocol in the conventional facsimile apparatus including the rejection of incoming-calls as described above. In FIG. 6, FAX-A sequentially performs calling for two transmissions to FAX-B, and FAX-C calls the FAX-A during the communication. It should be noted that in this case, an ISDN (Integrated Services Digital Network) line is used as a communication line.
The FAX-C performs redialing about two minutes after the initial rejection, however, the next call is rejected again. In this case, the FAX-C should perform redialing between (1-a) (termination of the first communication) and (1-b) (beginning of the next communication) so that the call from the FAX-C can be accepted. However, the interval between (1-a) and (1-b) is usually about ten seconds, therefore, the call from the FAX-C arrives during the next communication. As a result, the FAX-A subsequently being in busy status rejects the call from the FAX-C.